A private cloud is a cloud platform reserved for the use of one organization. Public clouds are — by definition — a shared infrastructure platform. Many organizations can deploy virtual servers on a public cloud, and each virtual server will share a physical server with instances owned by other organizations. Private clouds have many of the benefits of a public cloud — virtualized infrastructure that can be deployed on demand — but all the resources of the physical layer are at the disposal of a single company.
Contrary to interminable debates in the early days of cloud computing, neither public or private are superior as cloud modalities. Each has a specific domain of application in which it shines. But how does an organization know which modality is right for their use case?
Public clouds are flexible in terms of the virtual servers they run, but the flexibility of a private cloud goes well beyond that. Private clouds can be designed to suit the specific needs of an organization and the software deployed on them tailored for particular applications.
Whereas public clouds offer a fixed set of alternatives for infrastructure deployment, a private cloud can be used to build an entirely custom virtual environment.
This one may seem somewhat obvious, but private clouds are genuinely private. For some companies, guaranteed infrastructure privacy is an important factor in their choice of cloud modality. They want to know that their workloads are running on systems that they control and have insight into. A typical infrastructure strategy might mix public and private components, with high-value or sensitive workloads being limited to a private cloud.
While it’s rare, public cloud platforms can occasionally suffer from server or network contention issues that cause each server to have access to fewer resources than is optimal. That’s not usually a problem, because it can be managed by migrating virtual servers to other physical nodes or spinning up new servers, but if a company has an application that requires maximum performance with predictable consistency, a private cloud is almost certainly the right choice.
While it’s perfectly possible to comply with most regulatory frameworks that impact infrastructure hosting users on a public cloud, it’s often easier to achieve certifications and regulatory compliance if your organization can demonstrate that its computing resources are isolated from the wider world. Private clouds are inherently isolated, and may be the best choice for an organization that stores and processes sensitive data.
Public and private clouds are not competing modalities, but part of a cohesive cloud strategy that properly leverages the specific benefits of each.